Paper feed control apparatus and image forming apparatus

ABSTRACT

In a paper feed apparatus, a CPU  211  functionally includes: an abnormality detector ( 211   a ) that detects whether or not abnormal transport of recording paper is occurring in a paper feed path via which recording paper is transported from the paper feed apparatus to a main apparatus; a cover state detector ( 211   b ) that detects whether or not a cover is in a closed state; a lowered position setter ( 211   c ) that, when the cover is operated from the closed state to an open state, sets a lowered position of an electrically movable tray based on the detection result from the abnormality detector ( 211   a ); and an up/down movement controller ( 211   e ) that, when the cover is detected to be operated from the closed state to the open state, controls an up/down motor ( 222 ) to move the electrically movable tray down into the lowered position set by the lowered position setter ( 211   c ).

This application is based on Japanese Patent Application No. 2006-047698 filed on Feb. 24, 2006, the contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a paper feed control apparatus for controlling up/down movement of an electrically movable tray in a paper feed apparatus including: the electrically movable tray on which a supply of sheet-form recording paper is loaded in a stack and that is positioned at a predetermined paper feed position when recording paper is fed to a main apparatus; and a cover that can be operated between an open state and a closed state and that is brought into the open state when the supply of recording paper on the electrically movable tray is replenished and when abnormal transport of recording paper is dealt with that is occurring in a paper feed path via which recording paper is fed from the paper feed apparatus to the main apparatus. The present invention also relates to an image forming apparatus provided with a paper feed apparatus incorporating such a paper feed control apparatus. More generally, the present invention relates to copiers, printers, facsimile machines, and internet facsimile machines, and also to multifunction products equipped with one or more of the functions of those devices.

2. Description of Related Art

The recent trend toward faster printing speeds in image forming apparatuses such as copiers and printers has been increasing the consumption of recording paper per unit time (e.g., per month), requiring the users to replenish the supply of recording paper in their image forming apparatuses more frequently, and hence adding to their trouble. As an effort to reduce the frequency of recording paper replenishment, large-capacity paper feed apparatuses (e.g., with a capacity of 1 000 sheets) have been proposed and put to practical use.

As disclosed in, for example, JP-2004-159069, a large-capacity paper feed apparatus is furnished with an electrically movable tray that moves up and down with a large number of sheets of recording paper loaded on it and a cover that is opened when the supply of recording paper is replenished. When the supply of recording paper is replenished, as the cover is opened, the electrically movable tray moves down to its lower movement limit; as the cover is closed, the electrically movable tray moves up to its paper feed position.

Here, since the electrically movable tray moves up and down with a large number of (e.g., 1 000) sheets of recording paper loaded on it, it is so controlled as to move up slowly to save the electric capacity needed. Moreover, when abnormal transport of recording paper, such as a paper jam, occurs, opening the cover causes the electrically movable tray to move down to its lower movement limit as described above unnecessarily. Thus, having rectified the paper jam or the like, the user then has to wait for the electrically movable tray to move from the lower movement limit to the paper feed position before he can use the image forming apparatus again; that is, a wait is imposed on the user.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a paper feed control apparatus and an image forming apparatus that operate with a reduced wait imposed on the user having rectified a paper jam or the like.

To achieve the above object, according to a first aspect of the invention, a paper feed control apparatus for controlling up/down movement of an electrically movable tray in a paper feed apparatus includes: the electrically movable tray on which a supply of sheet-form recording paper is loaded in a stack and that is positioned at a predetermined paper feed position when recording paper is fed to a main apparatus; and a cover that can be operated between an open state and a closed state and that is brought into the open state when the supply of recording paper on the electrically movable tray is replenished and when abnormal transport of recording paper is dealt with that is occurring in a paper feed path via which recording paper is fed from the paper feed apparatus to the main apparatus. Here, the paper feed control apparatus is further provided with: an abnormality detecting portion that detects whether or not abnormal transport of recording paper is occurring in the paper feed path; a cover state detecting portion that detects whether or not the cover is in the closed state or not; a lowered position setting portion that sets the lowered position into which the electrically movable tray is moved based on the detection result from the abnormality detecting portion when the cover is operated from the closed state to the open state; and an up/down movement controlling portion that moves the electrically movable tray down into the lowered position set by the lowered position setting portion when the cover is operated from the closed state to the open state.

With this paper feed control apparatus, when the cover is operated from the closed state to the open state, based on the detection result of whether or not abnormal transport of recording paper is occurring, the lowered position of the electrically movable tray is set, and the electrically movable tray is moved down into the so set lowered position. Thus, when abnormal transport of recording paper is occurring, the lowered position can be set at a position higher than the lower movement limit at which the electrically movable tray is positioned when the supply of recording paper is replenished. This reduces the time needed after abnormal transport such as a paper jam is rectified until the electrically movable tray reaches the paper feed position, and thus reduces the wait imposed on the user.

According to a second aspect of the invention, the paper feed control apparatus may be so configured that, when the abnormality detecting portion detects abnormal transport, the lowered position setting portion sets the lowered position of the electrically movable tray near the paper feed position.

With this paper feed control apparatus, when abnormal transport is detected, the lowered position of the electrically movable tray is set near its paper feed position. This further reduces the time needed after abnormal transport such as a paper jam is rectified until the electrically movable tray reaches the paper feed position, and thus further reduces the wait imposed on the user.

According to a third aspect of the invention, the paper feed control apparatus may be further provided with an accepting portion that accepts an operation input from outside relating to the lowered position so that the lowered position setting portion sets the lowered position into which the electrically movable tray is moved when the abnormality detecting portion detects abnormal transport based on the operation input accepted by the accepting portion.

With this paper feed control apparatus, when abnormal transport is detected, the lowered position of the electrically movable tray is set based on the operation input. This allows the user to set the lowered position as he likes it, and thus improves user convenience.

According to a fourth aspect of the invention, the paper feed control apparatus may be so configured that, so long as the abnormality detecting portion does not detect abnormal transport, the lowered position setting portion sets the lowered position of the electrically movable tray at its lower movement limit.

With this paper feed control apparatus, so long as no abnormal transport is detected, the lowered position of the electrically movable tray is set at its lower movement limit. This makes it easy to replenish the supply of recording paper.

According to a fifth aspect of the invention, the paper feed control apparatus may be so configured that, when the cover is operated from the open state to the closed state, the up/down movement controlling portion moves the electrically movable tray up into the paper feed position.

With this paper feed control apparatus, even when abnormal transport is detected, if the cover is operated from the open state to the closed state, the electrically movable tray is moved up into the paper feed position. This improves user convenience.

According to a sixth aspect of the invention, the paper feed control apparatus may be so configured that the abnormality detecting portion detects a paper jam as abnormal transport.

With this paper feed control apparatus, paper jams, which occur commonly, can be detected as abnormal transport This further improves user convenience.

According to another aspect of the invention, an image forming apparatus is provided with: a paper feed apparatus including the paper feed control apparatus according to the first aspect of the invention; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.

With this image forming apparatus, thanks to the provision of the paper feed apparatus including the paper feed control apparatus according to the first aspect of the invention, it is possible to reduce the wait imposed on the user having rectified abnormal transport such as a paper jam.

According to another aspect of the invention, an image forming apparatus is provided with: a paper feed apparatus including the paper feed control apparatus according to the second aspect of the invention; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.

With this image forming apparatus, thanks to the provision of the paper feed apparatus including the paper feed control apparatus according to the second aspect of the invention, it is possible to reduce the wait imposed on the user having rectified abnormal transport such as a paper jam.

According to another aspect of the invention, an image forming apparatus is provided with: a paper feed apparatus including the paper feed control apparatus according to the third aspect of the invention; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.

With this image forming apparatus, thanks to the provision of the paper feed apparatus including the paper feed control apparatus according to the third aspect of the invention, it is possible to reduce the wait imposed on the user having rectified abnormal transport such as a paper jam.

According to another aspect of the invention, an image forming apparatus is provided with: a paper feed apparatus including the paper feed control apparatus according to the fourth aspect of the invention; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.

With this image forming apparatus, thanks to the provision of the paper feed apparatus including the paper feed control apparatus according to the fourth aspect of the invention, it is possible to reduce the wait imposed on the user having rectified abnormal transport such as a paper jam.

According to another aspect of the invention, an image forming apparatus is provided with: a paper feed apparatus including the paper feed control apparatus according to the fifth aspect of the invention; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.

With this image forming apparatus, thanks to the provision of the paper feed apparatus including the paper feed control apparatus according to the fifth aspect of the invention, it is possible to reduce the wait imposed on the user having rectified abnormal transport such as a paper jam.

According to another aspect of the invention, an image forming apparatus is provided with: a paper feed apparatus including the paper feed control apparatus according to the sixth aspect of the invention; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.

With this image forming apparatus, thanks to the provision of the paper feed apparatus including the paper feed control apparatus according to the sixth aspect of the invention, it is possible to reduce the wait imposed on the user having rectified abnormal transport such as a paper jam.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically showing an example of the configuration of an image forming apparatus according to the invention;

FIG. 2 is a perspective view of an example of a paper feed apparatus;

FIG. 3 is a structure diagram illustrating an example of how a paper feed position is controlled in the paper feed apparatus along with other features;

FIG. 4 is a functional configuration diagram showing an example of the functional configuration of a main controller and a paper feed controller; and

FIG. 5 is a flow chart showing an example of how the paper feed controller operates.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, an example of an image forming apparatus according to the invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram schematically showing the configuration of an image forming apparatus according to the invention. The following description deals with an example where the image forming apparatus is a printer; it should however be understood that the image forming apparatus may be any other kind of image forming apparatus that forms an image on recording paper (e.g., a copier, facsimile machine, internet facsimile machine, or multifunction product). As shown in FIG. 1, the printer 10 is composed of a main apparatus 1 and a paper feed apparatus 2. The main apparatus 1 includes a main controller 11, a print processor 12, and an operated portion 13. The paper feed apparatus 2 includes a paper feed controller 21 and a paper feed processor 22. The printer 10 is connected to an unillustrated personal computer (PC) so that these can communicate with each other, and the printer 10 forms an image on recording paper according to print instructions from the personal computer.

The main controller 11 controls the operation of the printer 10 as a whole, and includes a CPU (central processing unit) 111, a RAM (random-access memory) 112, and an unillustrated ROM (read-only memory). The main controller 11 feeds the paper feed controller 21 with instructions related to the control of the paper feed apparatus 2, and the paper feed controller 21 controls the operation of the paper feed apparatus 2 according to the instructions from the main controller 11.

The print processor 12 (corresponding to a printing portion) forms an image (here, an image according to image data received from the PC) on recording paper electrophotographically, and includes a developer unit 121, a photoconductor unit 122, and a fixer unit 123. According to image data received from the PC, the developer unit 121 forms an electrostatic latent image on the surface of a photoconductor drum with a laser beam or the like; the developer unit 121 then attaches toner to the so formed electrostatic latent image to form a toner image. That is, the developer unit 121 includes a photoconductor drum; first, the surface of the photoconductor drum is electrically charged by a charging roller substantially uniformly; next, to an electrical latent image formed according to image data received from the PC, toner is attached by the developer unit 121 to form a toner image; then, the toner image is transferred onto recording paper. The fixer unit 123 includes a fixing roller with which it fixes the toner image formed on the photoconductive drum.

The operated portion 13 (corresponding to part of an accepting portion) accepts operation inputs from the user, and to that end includes a plurality of operation buttons. As these buttons are operated, the operated portion 13 recognizes corresponding instructions, which it then feeds to the CPU 111. Here, the instructions recognized by the operated portion 13 includes, as will be described later, those related to the lowered position of an electrically movable tray.

The paper feed controller 21 (corresponding to part of a paper feed control apparatus) controls the operation of the paper feed apparatus 2, and includes a CPU 211, a RAM 212, and an unillustrated ROM. The paper feed controller 21 controls the operation of the paper feed apparatus 2 according to instructions from the main controller 11.

The paper feed processor 22 feeds sheet-form recording paper to the main apparatus 1, and includes a cover state sensor 221 and an up/down motor 222. The cover state sensor 221 (corresponding to part of the paper feed control apparatus) detects whether a cover 224, described later (see FIG. 2), is in an open or closed state, and feeds the detection result to the paper feed controller 21. The up/down motor 222 (corresponding to part of the paper feed control apparatus) moves an electrically movable tray 223, described later, up and down according to instructions from the paper feed controller 21.

FIG. 2 is a perspective view showing an example of the paper feed apparatus 2, and FIG. 3 is a structure diagram illustrating how the paper feed position is controlled in the paper feed apparatus 2 along with other features. As shown in FIG. 2, the paper feed apparatus 2 (paper feed processor 22) includes, in addition to the cover state sensor 221 and the up/down motor 222, an electrically movable tray 223, a cover 224, slits 225 (of which only one appears in the figure), and slider members 226 (of which only one appears in the figure). The cover 224 has, formed in a left side upright part 224 a thereof, a sensor pressing projection 224 b for pressing the cover state sensor 221.

The cover state sensor 221 (corresponding to part of a cover state detecting portion) is, for example, a push switch. When the user brings the cover 224 into the closed state, the cover state sensor 221 is pressed by the sensor pressing projection 224 b formed on the cover 224, thereby detecting the cover 224 to be in the closed state.

The up/down motor 222 operates according to instructions from the paper feed controller 21, and moves the electrically movable tray 223 in the direction (vertical direction) indicated by arrow B in FIG. 3 (moves it up and down). The up/down motor 222 achieves this via a power train including, for example, a gear, a belt, and the slider members 226, to which a central portion of the electrically movable tray 223 is fixed.

The electrically movable tray 223 has a supply of sheet-form recording paper loaded on it in a stack. When recording paper is fed to the main apparatus 1, according to an instruction from the paper feed controller 21, the electrically movable tray 223 is positioned in a predetermined paper feed position (such that the top end of the recording paper loaded on the electrically movable tray 223 is at the level indicated by arrow A in FIG. 3).

The cover 224 can be freely operated between an open and a closed state. The user brings the cover 224 into the open state when replenishing the supply of recording paper on the electrically movable tray 223, and when dealing with abnormal transport of recording paper (here, a paper jam) occurring in the paper feed path (indicated by arrow A in FIG. 3) via which recording paper is fed to the main apparatus 1.

The slits 225 are vertically extending guide grooves formed in side plates of the paper feed apparatus 2. The slider members 226 are guided along the slits 225 to move up and down, and a central portion of the electrically movable tray 223 is fixed to the slider members 226. That is, the driving power of the up/down motor 222 is transmitted to the slider members 226 so that the slider members 226 are guided along the slits 225 to move up and down, thereby making the electrically movable tray 223 fixed to the slider members 226 move up and down.

As shown in FIG. 3, the paper feed apparatus 2 (paper feed processor 22) further includes an abnormal transport sensor 227, a movable lever 228, and a paper feed position sensor 229. The abnormal transport sensor 227 (corresponding to part of an abnormality detecting portion) is, for example, a transmissive (or reflective) photosensor, and detects whether or not recording paper is present at a predetermined position in the paper transport path. As will be described later with reference to FIG. 4, the abnormal transport sensor 227 also detects a paper jam at the predetermined position in the paper transport path.

The paper feed position sensor 229 is, for example, a transmissive photosensor. The movable lever 228 and the paper feed position sensor 229 (together corresponding to part of an up/down movement controlling portion) detect whether or not the recording paper loaded on the electrically movable tray 223 is in the paper feed position. Specifically, the movable lever 228 is a bar-shaped lever that rotates about a predetermined point to keep constant contact with the top end of the recording paper loaded on the electrically movable tray 223 (or with the electrically movable tray 223 itself). When the recording paper is not in the paper feed position, the movable lever 228 interrupts the light path of the paper feed position sensor 229; when the recording paper is in the paper feed position, the movable lever 228 remains out of the light path of the paper feed position sensor 229.

FIG. 4 is a functional configuration diagram showing an example of the functional configuration of the main controller 11 and the paper feed controller 21. The CPU 111 functionally includes an operation accepter 111 a. The CPU 211 functionally includes an abnormality detector 211 a, a cover state detector 211 b, a lowered position setter 211 c, an accepter 211 d, and an up/down movement controller 211 e.

Here, the CPUs 111 and 211 read and execute programs previously stored in the ROMs or elsewhere to function as functional blocks such as the operation accepter 111 a, the abnormality detector 211 a, the cover state detector 211 b, the lowered position setter 211 c, the accepter 211 d, and the up/down movement controller 211 e.

Of the various kinds of data stored in the RAMs 112 and 212 and the ROMs, any part that can be stored on a removable recording medium may be read from a drive compatible with the medium, such as a hard disk drive, optical disc drive, flexible disk drive, silicon disc drive, or cassette medium reader, in which case the recording medium used may be, for example, a hard disk, optical disc, flexible disk, CD, DVD, or semiconductor memory.

The operation accepter 111 a (corresponding to part of the accepting portion) accepts operation inputs (specifically, those related to the lowered position, described later, of the electrically movable tray 223) from the user via the operated portion 13, and then feeds the instructions corresponding to the so accepted operation inputs to the lowered position setter 211 c of the paper feed controller 21. Specifically, in the operated portion 13, there are arranged, for example, a numeric keypad, an LCD (liquid crystal display), and an “set” button. As the numerical keypad is operated, the operation accepter 111 a displays the entered figures on the LCD; when the “set” key is then pressed, the operation accepter 111 a accepts the entered figures as a value indicating the lowered position (e.g., a position lower than the paper feed position by that value (mm)).

Based on the detection result from the abnormal transport sensor 227, the abnormality detector 211 a (corresponding to part of the abnormality detecting portion) detects whether or not abnormal transport of recording paper is occurring in the path via which recording paper is fed from the paper feed apparatus 2 to the main apparatus 1. Specifically, a predetermined time (e.g., five seconds) after recording paper starts to be fed, if the abnormal transport sensor 227 detects recording paper to be present at a predetermined position in the paper transport path, a paper jam, which is one form of abnormal transport, is detected to be occurring.

Based on the detection result from the cover state sensor 221, the cover state detector 211 b detects whether or not the cover 224 is in the closed state; that is, based on the detection result from the cover state sensor 221, the cover state detector 211 b detects the cover 224 to be operated from the closed to the open state, and detects the cover 224 to be operated from the open to the closed state.

When the cover state detector 211 b detects the cover 224 to be operated from the closed to the open state, the lowered position setter 211 c sets the lowered position of the electrically movable tray 223 (i.e. its position into which it is moved down when the cover 224 is operated from the closed to the open state) based on the detection result from the abnormality detector 211 a. Specifically, if the abnormality detector 211 a detects abnormal transport, the lowered position setter 211 c sets the lowered position near the paper feed position (hereinafter referred to as the first lowered position); if the abnormality detector 211 a detects no abnormal transport, the lowered position setter 211 c sets the lowered position at the lower movement limit of the electrically movable tray 223 (hereinafter referred to as the second lowered position). The lowered position setter 211 c sets the first lowered position based on an operation input accepted by the accepter 211 d. The first lowered position is located, for example, 10 mm below the paper feed position.

The accepter 211 d accepts operation inputs (specifically, those relating to the lowered position, described later, of the electrically movable tray 223) from the user via the operated portion 13 and the operation accepter 111 a, and feeds instructions corresponding to the so accepted inputs to the lowered position setter 211 c.

The up/down movement controller 211 e controls the up/down motor 222 so that, when the cover state detector 211 b detects the cover to be operated from the closed to the open state, the electrically movable tray 223 moves down into the lowered position (first or second lowered position) set by the lowered position setter 211 c and, when the cover state detector 211 b detects the cover to be operated from the open to the closed state, the electrically movable tray 223 moves up into the paper feed position.

FIG. 5 is a flow chart showing an example of the operation of the paper feed controller 21. Here, for the sake of simplicity, it is assumed that the first lowered position has already been accepted by the accepter 211 d and is stored in a predetermined memory (e.g., the RAM 212). At the start of the flow, the cover state detector 211 b checks whether or not the cover 224 is operated from the closed to the open state (S101). So long as the cover 224 is not found to be operated from the closed to the open state (“NO” in S101), a standby state is maintained. On the other hand, if the cover 224 is found to be operated from the closed to the open state (“YES” in S101), then the abnormality detector 211 a checks whether or not abnormal transport is occurring (S103). If abnormal transport is found to be occurring (“YES” in S103), the lowered position setter 211 c acquires the data of the first lowered position from the predetermined memory (S105), and sets it as the lowered position; the up/down movement controller 211 e then controls the up/down motor 222 so that the electrically movable tray 223 moves down into the position (lowered position) corresponding to the data of the first lowered position acquired in step S105 (S107).

On the other hand, if no abnormal transport is found to be occurring (“NO” in step S103), the up/down movement controller 211e sets the second lowered position as the lowered position, and controls the up/down motor 222 so that the electrically movable tray 223 moves down into the second lowered position (S109). On completion of the operation in step S107 or S109, the cover state detector 211 b checks whether or not the cover 224 is operated from the open to the closed state (S111). So long as the cover 224 is not found to be operated from the open to the closed state (“NO” in S111), a standby state is maintained. On the other hand, when the cover 224 is found to be operated from the open to the closed state (“YES” in S111), the up/down movement controller 211 e controls the up/down motor 222 so that the electrically movable tray 223 moves up into the paper feed position (S113). When the electrically movable tray 223 reaches the paper feed position (i.e. on completion of the operation in step S113), the flow ends.

In this way, when the cover 224 is operated from the closed to the open state, based on the detection result of whether or not abnormal transport of recording paper is occurring, the lowered position of the electrically movable tray 223 is set, and the electrically movable tray 223 is moved into the so set lowered position. Thus, when abnormal transport of recording paper is occurring, the lowered position can be set at a position higher than the lower movement limit of the electrically movable tray 223 in which it is positioned when the supply of recording paper is replenished. This reduces the time needed after abnormal transport such as a paper jam is rectified until the electrically movable tray 223 reaches the paper feed position, and thus reduces the wait imposed on the user.

Moreover, when abnormal transport is detected, the lowered position of the electrically movable tray 223 is set near the paper feed position. This further reduces the time needed after abnormal transport such as a paper jam is rectified until the electrically movable tray 223 reaches the paper feed position, and thus further reduces the wait imposed on the user. Furthermore, the lowered position of the electrically movable tray 223 where it is positioned when abnormal transport is detected is set based on an operation input. This allows the user to set the lowered position as he likes it, and thus improves user convenience.

In addition, when no abnormal transport is detected, the lowered position of the electrically movable tray 223 is set at its lower movement limit. This makes it easy to replenish the supply of recording paper. Even when abnormal transport is detected, if the cover 224 is operated from the open to the closed state, the electrically movable tray 223 is moved up into the paper feed position. This improves user convenience. Moreover, paper jams, which occur commonly, can be detected as abnormal transport This further improves user convenience.

The present invention allows many modifications and variations, of which some examples are as follows:

Although the embodiment described above deals with an example where the paper feed apparatus 2 includes a CPU 211, it is also possible, instead of providing the paper feed apparatus 2 with a CPU 211, to provide the CPU 111 of the main apparatus 1 (main controller 11) with a abnormality detector 211 a, a cover state detector 211 b, a lowered position setter 211 c, a accepter 211 d, and a abnormality detector 211 a. This allows all control to be performed by the CPU 111 in a centralized fashion, and thus helps simplify the processing.

Although the embodiment described above deals with an example where the CPU 211 of the paper feed apparatus 2 (paper feed controller 21) is provided with an abnormality detector 211 a, it is instead also possible to provide the CPU 111 of the main apparatus 1 (main controller 11) with a abnormality detector 211 a. This allows abnormal transport of recording paper in the entire printer 10 to be managed by the CPU 111 in a centralized fashion. In that case, it should be noted, the detection result of whether or not abnormal transport is occurring needs to be fed from the CPU 111 to the CPU 211 (lowered position setter 211 c).

Although the embodiment described above deals with an example where the first lowered position is accepted by the accepter 211 d, it is instead also possible to set the first lowered position beforehand. This helps simplify the processing.

Although the embodiment described above deals with an example where the different functional blocks essential to the invention are functionally included in the CPUs 111 and 211, that is, realized on a software basis, it is also possible to realize those functional blocks on a hardware basis, for example with electronic circuits built to function as such functional blocks. 

1. A paper feed control apparatus for controlling up/down movement of an electrically movable tray in a paper feed apparatus including: the electrically movable tray on which a supply of sheet-form recording paper is loaded in a stack and that is positioned at a predetermined paper feed position when recording paper is fed to a main apparatus; and a cover that can be operated between an open state and a closed state and that is brought into the open state when the supply of recording paper on the electrically movable tray is replenished and when abnormal transport of recording paper is dealt with that is occurring in a paper feed path via which recording paper is fed from the paper feed apparatus to the main apparatus, the paper feed control apparatus comprising: an abnormality detecting portion that detects whether or not abnormal transport of recording paper is occurring in the paper feed path; a cover state detecting portion that detects whether or not the cover is in the closed state or not; a lowered position setting portion that sets a lowered position into which the electrically movable tray is moved based on a detection result from the abnormality detecting portion when the cover is operated from the closed state to the open state; and an up/down movement controlling portion that moves the electrically movable tray down into the lowered position set by the lowered position setting portion when the cover is operated from the closed state to the open state.
 2. The paper feed control apparatus of claim 1, wherein, when the abnormality detecting portion detects abnormal transport, the lowered position setting portion sets the lowered position of the electrically movable tray near the paper feed position.
 3. The paper feed control apparatus of claim 1, further comprising: an accepting portion that accepts an operation input from outside relating to the lowered position, wherein the lowered position setting portion sets the lowered position into which the electrically movable tray is moved when the abnormality detecting portion detects abnormal transport based on the operation input accepted by the accepting portion.
 4. The paper feed control apparatus of claim 1, wherein, so long as the abnormality detecting portion does not detect abnormal transport, the lowered position setting portion sets the lowered position of the electrically movable tray at a lower movement limit thereof.
 5. The paper feed control apparatus of claim 1, wherein, when the cover is operated from the open state to the closed state, the up/down movement controlling portion moves the electrically movable tray up into the paper feed position.
 6. The paper feed control apparatus of claim 1, wherein the abnormality detecting portion detects a paper jam as abnormal transport.
 7. An image forming apparatus comprising: a paper feed apparatus including the paper feed control apparatus of claim 1; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.
 8. An image forming apparatus comprising: a paper feed apparatus including the paper feed control apparatus of claim 2; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.
 9. An image forming apparatus comprising: a paper feed apparatus including the paper feed control apparatus of claim 3; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.
 10. An image forming apparatus comprising: a paper feed apparatus including the paper feed control apparatus of claim 4; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.
 11. An image forming apparatus comprising: a paper feed apparatus including the paper feed control apparatus of claim 5; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus.
 12. An image forming apparatus comprising: a paper feed apparatus including the paper feed control apparatus of claim 6; and a printing portion that forms according to image data an image on recording paper fed from the paper feed apparatus. 